Lumpy running in top gear - S3 2.9 cc V6!???

[Hoss]

Cruising along in top at about 50-60 mph and if light acceleration is applied, causes lumpy running as though the engine is labouring. I have always had the problem and driven accordingly but recently it has got worse. New plug and air filter fitted, but no change. Any ideas out there guys???

[harry1972m]

Could be throttle potentiometer - if you do a search on this or throttle pot as there commonly called you will find massive amounts of info - you should disconnect the connector to the TP which will put the engine into a get home mode - if your problem dissapears then you have just diagnosed the fault.

Cheers
Graham

[chrischat]

i have a very similar fault on my S3. At a steady 3500 rpm in top if you apply more gas it feels lumpy like the choke has come on, and the gearlever starts rattling around. Change down to 3rd or 4th and floor it then it's fine. Tick over is ok and up through the gears from standstill is good. I was thinking plugs but now maybe not. Does it mean the expense of a rolling road session ?

[harry1972m]

If it is the TP then a straight swap for a new one - a 5 minute job - will cure it - it did for me.

Cheers
Graham

[spivvy]

changed TP didn't appear to sort my problem out

[foxy600]

Could be the air flow meters, go to Northampton Motorsport and they will set them up...this may sort the problem

PS. Ask for Chris, he has a Transit with a cologne engine so he knows what he is doing!!

Edited by foxy600 on Tuesday 24th April 09:54

[harry1972m]

When I had this sort of problem a year or so back it was actually both the TP and the AFM,s so diagnosis was difficult indeed - again you can also disconnect the AFM only one at a time though and see if this solves it - if it does then maybe start by cleaning the internal wire very gently with carb cleaner.